This invention relates generally to trailer hitch couplings and assemblies of the ball and socket type and, more particularly, to an improved trailer hitch assembly that has an automatic and positively locking function which obviates the need for manipulation of a latch or lever by the user to lock the assembly onto a vertically-projecting ball at the rear of a towing vehicle.
A self-locking trailer hitch assembly is disclosed in U.S. Pat. No. 4,209,184 issued Jun. 24, 1980. That assembly disclosed structure for achieving an automatic locking function as an incident of placing the coupler on the ball member. However, the design has proven to be both structurally and aesthetically unacceptable because a feature of that structure is its susceptibility to being induced to lock without the ball member being properly contained within the socket if the assembly is inadvertently positioned too far forward over the ball by the user when bringing the assembly into a hitching position. This occurs when the assembly is positioned above the upwardly-projecting ball member, but with the socket forward of the ball member; as the assembly is lowered onto the ball member, a jaw retainer component is forced into a locking disposition by the forcible contact of the ball member thereagainst as the user unsuccessfully attempts to hitch the assembly to the ball member.
Therefore, there is a need for a self-locking trailer hitch assembly which avoids inadvertent coupling action and also locks onto the ball member without requiring user manipulation of latches or levers to actuate the locking and coupling action of the assembly.